Tens of thousands of people have marched through London demanding action on poverty, climate change and jobs, ahead of next week's G20 summit.

Marchers from all walks of life were united in their belief that the current global economic system was simply not working and change was urgently needed.

With many facing an uncertain employment future, trust in the financial institutions and in politicians has evaporated.

Union leader Derek Simpson said sweeping reforms are needed right now. "It is not just about business. It is not just about commerce and bankers, it is about people. Putting people first, that is the message. We need to do more about jobs in this country, more to protect people's homes in this country and this demonstration is a means of bringing it to the government's attention," he said.

At least 35,000 made the march from the banks of the Thames, to parliament, to Ten Downing Street and then, on to Hyde Park and among those in the crowd were university students like Rob Owen. "What is incredibly positive about the way the demonstration has come together is it is different groups of workers, students, different people that are affected by the crisis that is kind of gripping the system, actually coming together to say that collectively we can fight back and argue to put out priorities first," he said.

The current job market for graduates is the worst in decades, and fellow student Hannah Sell said many marched out of a sense of anger. "Ordinary people should not pay for this crisis. Capitalism is in crisis. The financiers are responsible and yet they are being bailed out, we are getting nothing," she said.

The march was really a prelude to others that will coincide with the so called G-20 summit of world leaders that will take place here on Thursday.

But the action will not stop there according to one of the organizers, Tony Robinson. "This is inviting people to take up the cause from now on. This time next year we will not have gone away. We will be making demands on politicians and they are going to have to listen," he said.

Similar demonstrations all were also staged in Berlin and Paris Saturday where marchers wanted to get their message across to their leaders before they head off to the summit.